Manufacture of rubber footwear



p 1934- L. H. BURNHAM r A L 1,972,976

MANUFAC'IZURE OF RUBBER FOOTWEAR Fild April 15, 19.31

15 WNW /9. V \F Smreniors; .Lawnencs H. Ewan/balm, 9*

R096)? 772. Holden v) W Aiiovmeu. 0

Patented Sept. 11, 1934 UNITED STATES PATENT EOFFIC mmaorons or RUBBER FOOTWEAR Laurence H. Burnham, Lexington,

Holden, Worcester, Mass;

and Roger M. said Bln'nham assetts 'Application April 13, 1931, Serial him-529,838

3 Claims.

The present invention relates to the manufacture of rubber foot wear, such as boots, overshoes and the like, and has for its object to provide an improved method of making such foot wear in an extremely economical and satisfactory manner.

In the manufacture of articles of rubber foot wear of various types, it is essential to employ some sort of lining in the nature of a fabric upon which to build the different parts, such assole, m vamp and leg pieces, after which the article is completed by vulcanizing. ne method of procedure heretofore extensive y practiced in the manufacture of rubber foot wear resides in suitably rubberizing large sheets of lining fabric, after which the sheets of material are out according to various patterns to provide separate pieces which are assembled upon the lasts to provide a base for the other parts. Obviously, the assembly of the lining parts on the lasts entails a considerable amount of labor, while the manufacture of different sizes of foot wear necessitates the provision in advance of large quantities of lining parts cut according to different patterns, with considerable waste of treated lining material.

Another mode of procedure is shown and described in our copending application, Serial No.

449,891 filed May 5 1930, wherein the manufacture of rubber articles of foot wear is characterized by the utilization of one-piece linings so knitted as to approximately conform to the shapes of the lasts on which the articles of foot wear are built up. In carrying out this method of manufacture, the other parts are built up directly on the linings, as supported by the lasts, after which the articles are vulcanized. However, for the successful practice of the method described in our aforesaid copending application in which the parts are built directly on the linings, it is essential that sufficient pressure be applied during vulcanizing to insure intimate contact of the parts with the lining whereby to obtain, in-efiect, an actual embedding of portions of the lining in the surrounding parts; otherwise, suflicient adhesion will not 4'5 be secured with the lining in the completed article of foot wear. But with this procedure, it has been found in some cases that the embedding of the linings. in the surrounding parts affects to a varying degree both the appearance of the exterior rubber 5 0 surfaces of the completed articles of foot wear, as

well as the interior surfaces of the linings.

Accordingto the present invention, the utilization of one-piece fabric linings is extended to include the manufacture of substantially all types of foot wear by any vulcanizing process, with or without pressure, through the rubberizing or the treatment with a suitable adhesive of the linings in advance of building the other parts of the articles thereon, as a result of which treatment greater and more uniform adhesion of the linings with the surrounding parts is obtained, than has heretofore been possible.

The above and other advantageous features of the invention from the standpoint of manufacturing efliciency will hereinafter more fully appear from the following description with reference to the accompanying drawing, in which:-

Fig. 1 is a view in side elevation of a one-piece lining to be used in carrying out our invention.

Fig. 2 is a view in side elevation illustrating the appearance of the lining after it has been drawn on a last.

Fig. 3 is a view in side elevation showing the lining covered last of Fig. 2 mounted for cooperation with the rubberizing apparatus.

Fig. 4 is a view similar to Fig. 2, showing the appearance of the lining after the rubberizing operation. A

Fig. 5 is a vertical section through a completed article.

Fig. 6 is a view in side elevation showing the lining of Fig. 1 drawn onto a different type of form.

Fig. '7 is a plan view illustrating the manner of rubberizing linings on the forms of Fig. 6.

Like reference characters refer to like parts in the different figures.

In carrying out the invention, a last 1 is provided, which as shown in Fig. 2 closely approximates the form of the article of foot wear to be produced, here shown as a boot. The one-piece lining 2, which is to be applied to the last 1, preferably consists of a length of tubular fabric knitted in such a manner as to initially conform approximately to the shape of the last 1, without being fashioned to correspond exactly thereto.

As an illustrative embodiment of the invention, the lining 2 is shown as having been produced on an ordinary hosiery machine with a single stitch and consists of a toe portion 3 knitted with continuous courses, while another portion 4 extending from the line a-b-to the line c-d is knitted with continuous courses 4a alternating with discontinuous courses 4b extending substantially halfway around the circumference of the portion 4. With this particular manner of knitting, as the portion 4 comes off the machine, the fabric takes the-form of a curve between the lines a-b and c-d, with the alternating continuous and discontinuous comses 4a and 4b im- 1 what longer than parting a considerably larger curvature to that side of theportion 4. The lining 2 also consists of a tubular portion knitted in continuous courses, preferably with the stitches thereof somethe stitches of the portion 3, so that the portion 5 tends to be larger in circumference towards its upper end. The exact manner of knitting a lining 2 having the above described form constitutes no part of the present invention, as seamed or seamless tubular fabric linings having an arcuate form may be produced in other ways, as by knitting courses of the portion 4 in dissimilar stitch; such linings being described in our aforesaid copending application, Serial No. 449,891. In order to complete the lining 2, the open edges of the portion 3 are brought together and sewn by threads 6 to provide a seam which'extends transversely to the axis of the portioii 3, with the stitches approximately the form of the curvature of the sole of the last 1, around the edge of the toe.

The next step in carrying out the invention resides in drawing the lining 2 over the last 1 which is supported in an inverted position at an angle of about so that the toe portion of the last will enter readily into the open end of the lining 2. By reason of its original form approximating that of the last 1, the lining 2 may be readily drawn thereon without appreciable stretching at anyplace so that it fits closely to the last 1 to prei sent a-smooth surface over all, with an entire aband around the heel of worm sence of wrinkles. When the lining 2 has been fully drawn on the last 1, it will be seen that the portion3, in which the stitches-are relatively tight, fits closely on the narrow toe portion of the last, with the toe seam stitches 6 curved. around the sole, so that they lie fiat. The arcuate portion 4 of the lining formed by the dissimilar courses 4a and 4b fits snugly to the heel and concave instep portion of the last, that portion with the extra partial courses extending along the sole the last. Above the instep andheel portion of the last, where it is of elliptical cross section and increasing circumference, the somewhat longer stitches of the lining portion 5 impart a certain amount of yield to the lining which enables it to take care of the increasing size of the last, without appreciable stretching.

The next step in the preferred form of our improved method of procedure is to mount the lining covered last '1 in a vertical position on a carrier 7 that is adapted to be rotated about a vertical axis in any suitable manner, as by. means of a rotatably driven worm 8 meshing with a wheel 9 mounted on the carrier '7. As the lining covered last turns slowly with the carrier '7, one or more nozzles 10 are adapted to coat the lining 2 with rubber dispersed in a liquid carrier, or other suitable adhesive of the desired consistency which is delivered in highly atomized form by the nozzles 10. The spray nozzles 10 are of any suitable design, best adapted for the purpose, each nozzle 10 being supplied with liquid adhesive through a pipe 11 and with air under pressure through a pipe, 12,

In carrying out the treatment of a lining 2,

a relatively light coat of adhesive is first applied quickly by turning the table 7 at the desired rate, the nozzles 10 being set at such a distance from the lining and the supply of adhesive being cut down to such an extent, that the adhesive tends to dry in passing from a nozzle to the lining. As a result of this control of the amount of adhesive and the rate' of spraying, a light adhesive By the time the first coat of adhesive is applied to the lining, it is so nearly dried that a second and heavier coat maybe applied immediately with the nozzles 10 opened wider toincrease ume of adhesive material in the spray. During the application of the second coat, the carrier '1 may be'rotated at a'reduced speed, as compared to its rate of rotation when applying the first coat, thereby resulting in a heavier application of adhesive. If desired, a third coat may be applied depending on the specific gravity of the material and its rate of drying, the net result of the several sprayings being the formation of a'coating 13 of adhesive over the outer surface of the entire lining. This coating 13 is uniform in character, as indicated in Fig. 4, and presents an unbroken surface-somewhat tacky or sticky. 1 I

After completion of the spraying, the last is removed from the carrier 7 and is then ready for the boot parts to be built up on the adhesive coated lining. In the formation of a boot, or other article of foot wear, on an adhesive coated one-piece lining, the different parts of which the boot is composed are built upon the lining with a flat sole in contact with the toe seam and with suitable leg and vamp pieces holding the sole in position. The last, with the boot parts adhered to the coated lining, is then placed in a suitable open cure vulcanizer and the boot is completed by vulcanizing. By reason of the smooth and-uniform char acter of the coating 13 over the one-piece lining, adequate adhesion uniform in character is obthe voltained between. the boot parts 14 and the lining 2' portioning the form 15, its width at diilerent points is determined by measuring the perimeter of the last 1 at different sections transverse to its axis and laying out these perimeters on a slightly reduced scale on the form 15. The resulting form 15 is of such shape that a lining 2 may be readily drawn over the same without appreciable stretching, with the lining presenting a smooth unwrinkled surface on both sides of the form.

As indicated in Fig. 7, a numberof forms 15 having linings drawn thereon are placed'on a conveyor ,16 which is adapted to slowly move the lining covered forms 15 between oppositely disposed spray nozzles 17. These nozzles 17 are so arranged as to spray adhesive over the surfaces of the distended linings and preferably the nozzles 1'7 are arranged in spaced groups so that there is an appreciable interval for drying between the application of successive coats of adhesive. Obviously, the drying between. successive coats can be accelerated by subjecting the sprayed linings Instead of drawing .each lining over a to air blasts from nozzles 18. Furthermore, it is desirable to reduce the amount of adhesive sprayed by the first group of nozzles 17, as compared to the next group of nozzles, so that there will be no possibility of the first coat of adhesive penetrating the linings. Obviously, the length of the conveyor 16 can be such as to insure that the coatings on the linings will be of just the right degree of tackiness by the time the forms 13 reach the end of the conveyor, whereupon the coated linings may be readily removed from the forms 15 and immediately drawn on lasts for the building of the other boot parts thereon. Or, if desired, the forms 15 with the coated linings thereon, or the coated linings themselves, can be removed from the conveyor immediately after the last spraying and stored. Obviously, a large number of coated linings on or off the fbrms 15 can be stored or transported in a relatively small space, as compared to the space that would be occupied by a corresponding number of full sized lasts.

From the foregoing, it is apparent that bythe practice of the present invention it is possible to utilize one-piece linings in the manufacture of all types of rubber foot wear by any desired process in an extremely economical manner with greater and more uniform adhesion than has heretofore been obtained with either pattern cut lining parts or untreated one-piece linings.

We claim,

1. The improvement in the manufacture of lined rubber foot wear which consists in pulling over a last an approximately shaped fabric linlast by placing separate uncured rubber parts of the article in contact with the adhesive coating, while the coating is in a tackycondition, and then curing said parts to uniformly adhere them to the coated lining.

2. A step in the process of manufacturing articles of rubber foot wear which consists in applying separate uncured rubber parts of the article to the uniformly adhesive coated fibrous surface of a unitary fabric lining mounted on a last, while said adhesive coating is in a tacky condition.

3. The improvement in the manufacture of lined rubber footwear, which consists in pulling over a flat form an approximately shaped fabric lining knitted to initially provide an arcuate poring separate uncured rubber parts of the article in contact with the coated lining while the adhesive is in a tacky condition and then curing said parts to uniformly adhere them to the coated lining. LAURENCE H. BURNHAM.

ROGER M. HOLDEN. 

